1. Field of the Invention
The present invention relates to a method of mounting components on a plurality of abutted circuit boards, and more particularly, to a method of mounting components on a plurality of abutted circuit boards that requires less steel plates, components mounters, and bills of material (BOM), and artworks.
2. Description of the Prior Art
Electronic products have proven to be indispensable tools in modern life and become popular with consumers, particularly gadgets that are made extra compact and mobile such as notebooks, personal digital assistants (PDA), cellular phones, and compact disc (CD) walkmans. As a result of the reduced volume of electronic products, circuit boards used in the electronic product must also have their volume reduced. In order to reduce the volume and encompass the same components on the circuit boards, manufacturers of circuit boards mount components on a front side and a rear side of a plurality of abutted circuit boards with two component mounters. Please refer to FIG. 1a and FIG. 1b. FIG. 1a and FIG. 1b are diagrams of a prior art method for mounting components on a dual circuit board 102. The dual circuit board 102 has a first circuit board 104 and a second circuit board 106. The first circuit board 104 and the second circuit board 106 are abutted along a separating line L. Each of the circuit boards 102, 104, 106 has a front side 102a, 104a, 106a and a rear side 102b, 104b, 106b. 
The front side 104a of the first circuit board 104 abuts on the front side 106a of the second circuit board 106. The first step of the method is to dispose the dual circuit board 102 in a component mounter 108a for mounting a plurality of components 110a on the front side 104a of the first circuit board 104 and mounting a plurality of components 110b on the front side 106a of the second circuit board 106.
For example, 300 components 110a are mounted on the front side 104a of the first circuit board 104, and 300 components 110b are mounted on the front side 106a of the second circuit board 106. Therefore, the front side 102a of the dual circuit board 102 has a total of 600 components. Before the dual circuit board 102 is disposed in the component mounter 108a, a first steel plate is positioned on the front side 104a of the first circuit board 104 and on the front side 106a of the second circuit board 106.
The first steel plate has a plurality of holes. Then, solder is applied onto the first steel plate so as to fill the holes with solder. After that, the first steel plate is removed so that a plurality of solder pads is mounted on the front side 104a of the first circuit board 104 and on the front side 106a of the second circuit board 106. Then, the dual circuit board 102 is placed in the component mounter 108a and infrared rays of high temperature is used to melt the solder pads such that the components 110a on the front side 104a of the first circuit board 104 and the components 110b on the front side 106a of the second circuit board 106 are soldered.
After finishing mounting components on the front side 102a of the dual circuit board 102, the dual circuit board 102 is turned over and then placed in another component mounter 108b for mounting a plurality of components 112a on the rear side 104b of the first circuit board 104 and mounting a plurality of components 112b on the rear side 106b of the second circuit board 106. For example, 40 components 112a are mounted on the rear side 104b of the first circuit board 104, and 40 components 112b are mounted on the rear side 106b of the second circuit board 106. Therefore, a rear side 102b of the dual circuit board 102 has a total of 80 components. Two separate circuit boards are formed after the separating dual circuit board 102 along the separating line L.
Before the dual circuit board 102 is placed in the component mounter 108b, a second steel plate is positioned on the rear side 104b of the first circuit board 104 and on the rear side 106b of the second circuit board 106. The second steel plate has a plurality of holes. Then, solder is applied onto the second steel plate so as to fill the holes with solder. The second steel plate is removed so that a plurality of solder pads is mounted on the rear side 104b of the first circuit board 104 and on the rear side 106b of the second circuit board 106. The dual circuit board 102 is placed in the component mounter 108b and the high temperature of infrared rays is used to melt down the solder pads so as to solder the components 112a on the rear side 104b of the first circuit board 104 and solder the components 112b on the rear side 106b of the second circuit board 106.
Please notice that the prior art method of mounting components on a dual circuit board 102 requires two bills of material (BOM) and two artworks corresponding to the component mounters 108a and 108b respectively. One bill of material is required when the component mounter 108a mounting the components 110a on the front side 104a of the first circuit board 104 and mounting the components 110b on the front side 106a of the second circuit board 106. The other bill of material is required when the component mounter 108b mounting the components 112a on the rear side 104b of the first circuit board 104 and mounting the components 112b on the rear side 106b of the second circuit board 106.
Similarly, one artwork is provided to operators for quality checking whether the components 110a on the front side 104a of the first circuit board 104 and the components 110b on the front side 106a of the second circuit board 106 are mounted in accordance with the artwork. The other artwork is provided to operators for checking whether the components 112a on the rear side 104b of the first circuit board 104 and the components 112b on the rear side 106b of the second circuit board 106 are mounted in accordance with the artwork.
However, the use of two sets of each production part increases the manufacturing cost considerably. The design of two component mounters, two steel plates, two bills of material, and two artworks increases the preparation required and also lengthens the production line.
Assume that the component mounters 108a and 108b can mount a component in one second. If the component mounters 108a and 108b work 86400 seconds each day, an expected number of products that the component mounters 108a and 108b within two days is:(1) The front side 102a of the dual circuit board 102 has a total of 600 components, so the component mounter 108a can finish 86400/600=144 semi-finished products per day.
(2) The rear side 102b of the dual circuit board 102 has a total of 80 components, so the component mounter 108b can finish 86400/80=1080 semi-finished products per day.
(3) Combined the counts from item (1) and (2), itindicates that 144*2=288 circuit boards can be finished within two days.
As mentioned above, during same given interval, the component mounting counts are significantly different between the front side and the rear side of the dual circuit board. In other words, the production rate of one side will always lag behind the other side of the dual circuit board. As a result, the prior art method has a limited maximum throughput of the circuit boards. Additionally, if there are four circuit boards, the difference between the front side and the rear side of the dual circuit board will become more significant.
It is therefore a primary objective of the claimed invention to provide a method for mounting components on a plurality of abutted circuit boards. The method requires less steel plates, components mounters, and bills of material (BOM), and artworks.
The numbers of components on the front side of the main abutted circuit board are the same as the number on the rear side of the main abutted circuit board. This allows the output levels of the two semi-finished products to match, increasing the output of the circuit boards. Therefore, the claimed invention can reduce the production work and cost, shorten the production line, solve the problem of unequal throughputs of the two semi-finished products, and increase the throughput of the circuit boards.
The claimed invention, briefly summarized, discloses a method for mounting components on a main abutted circuit board. The main abutted circuit board has N first circuit boards and N second circuit boards, where N is a positive integer. Each of the circuit boards has a front side and a rear side. The front sides of the first circuit boards abut on the rear sides of the second circuit boards.
The method comprises placing the main abutted circuit board in a component mounter for mounting a plurality of components on the front sides of the first circuit boards and mounting a plurality of components on the rear sides of the second circuit boards. The method further includes placing the main abutted circuit board in the component mounter for mounting a plurality of components on rear sides of the first circuit boards and mounting a plurality of components on front sides of the second circuit boards.
These and other objectives of the present invention will be apparent to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.